Screen sharing intermittently fails (or works)

We are new users of the free version of jitsi meet, and got a lot of problems this morning trying to share screens among 10 participants. The symptoms were a greenish background screen with à screen icon in the middle or the center circle with the initial of the participant instead of the expected shared screen (sorry, I do not have screen captures available at the moment).
Once the meeting was over we made more trials between two participants only… and everything worked just fine, using exactly the same procedure as we did previously.
Could it be possible that we faced a bandwidth problem, either on the network itself or at the jitsi site ?
Thank you.